An X-ray fluorescence spectrometer irradiates a sample in an analysis chamber with a primary X-ray emitted from an X-ray source, detects a fluorescent X-ray emitted from the irradiated sample by means of a detector, measures the wavelength (energy) and the intensity of a peak of the fluorescent X-ray, and thus performs a qualitative/quantitative analysis of element components in the sample. Here, if the atmospheric air exists in an optical path of the primary X-ray from the X-ray source to the sample as well as in an optical path of the fluorescent X-ray from the sample to the detector, the primary X-ray and the fluorescent X-ray are absorbed and attenuated by the atmospheric air. In particular, light elements whose atomic number is less than 23 each generate a fluorescent X-ray with a long wavelength (low energy), and are strongly influenced by such absorption by the atmospheric air. To deal with this, in the case where light elements are contain d in an analysis target, the atmosphere inside the analysis chamber is replaced with helium gas which absorbs less X-ray than the atmospheric air.
The analysis chamber is provided with a gas supply port and a gas outlet, and helium gas is supplied from the gas supply port while the atmospheric air is pushed out from the gas outlet, whereby the atmosphere inside the analysis chamber is replaced with the helium gas. In addition to the gas supply port and the gas outlet, the analysis chamber is provided with opened parts such as an introduction port for the primary X-ray emitted from the X-ray source and a detection port for the detector. Hence, conventionally, in order to prevent gases from flowing in and out through the opened parts, the opened parts are each covered by a thin organic whereby the helium gas replacement work is made more efficient (see Patent Literature 1).
In the above-mentioned conventional method, however, although organic films that absorbs less X-ray are used, the light elements, which each emit a fluorescent X-ray with a longer wavelength (lower energy) by irradiation with the primary X-ray, a e significantly influenced by the X-ray absorption due to the existence of the organic films in the optical path of the primary X-ray and the optical path of the fluorescent X-ray.